Feeds

Sinclair ZX Spectrum FAILS latest radio noise rules SHOCK

1980s tech for 1980s rules

SANS - Survey on application security programs

A pal of mine suggested a short while back that it might be fun to obtain the blueprints for Sinclair Research’s ZX Spectrum and have a batch built up to sell to fans of retro computing. It’s a good job this plan never made it out of the pub: the dear old Speccy would have immediately fallen foul of modern electromagnetic radiation interference regulations.

How do we know? Register reader and blogger Ben Supper recently put one of these early 1980s 8-bit micros into an EM test chamber to find out.

Ben writes that, to give the Spectrum a fighting chance of making it past the rigorous EN55022 standard test, he simply powered up the computer, not the associated TV, cassette recorder and the cables that connect them all together. He also disabled the test Spectrum’s TV modulator.

Says Ben: “Six complete frequency sweeps were taken, at three angles around the equipment in horizontal and vertical polarisations, with the antenna at a height of 1.5 metres.” That, he admits, was only the first part of the EN55022 test - the recent bad weather reduced the amount of time he had available in the test chamber which prevented him from running a full set of tests.

EN55022 test results
ZX Spectrum EN55022 test results

EN55022 output: a modern 'tricky' product (top) a not-so-modern product, the ZX Spectrum (bottom)
The thick black line is the test noise limit
Source: Ben Supper

Not that it would have made much difference.

Alas the leaky machine - from a radio standpoint - ensured the Spectrum did not pass the test. “It’s not just a failure; it’s an abject one,” admitted Ben.

The Spectrum radiated enough energy at two frequencies - 42MHz and 48.8MHz - to fail the test, but noise above 100MHz, while below the failure emission levels, could easily bust the limit if the Spectrum had been fully connected up, Ben reckons.

The 42MHz peak arises as a harmonic of the machine’s 3.5MHz clock frequency, while the 48.8MHz peak almost certainly arises from radiation emitted by the Spectrum’s “rather fishy power supply and cable”. It’s also an upper harmonic of the PAL colour clock.

Of course, the Spectrum would have been designed completely differently had it been created in modern times, quite apart from being built not to exceed EN55022 noise levels. Back in the early 1980s, the Spectrum's electronics man, Richard Altwasser - who went on to design the Jupiter Ace - didn't have quite so many regulations to worry about. More to the point, now he might not have Sir Clive being quite so insistent that the kit be as cheap as possible.

You can read Ben's write-up of the test, and the background to it, here. ®

SANS - Survey on application security programs

More from The Register

next story
WTF happened to Pac-Man?
In his thirties and still afraid of ghosts
Reg man builds smart home rig, gains SUPREME CONTROL of DOMAIN – Pics
LightwaveRF and Arduino: Bright ideas for dim DIYers
Leaked pics show EMBIGGENED iPhone 6 screen
Fat-fingered fanbois rejoice over Chinternet snaps
Microsoft signs Motorola to Android patent pact – no, not THAT Motorola
The part that Google never got will play ball with Redmond
Happy 25th birthday, Game Boy!
Monochrome handset ushered in modern mobile gaming era
Rounded corners? Pah! Amazon's '3D phone has eye-tracking tech'
Now THAT'S what we call a proper new feature
Zucker punched: Google gobbles Facebook-wooed Titan Aerospace
Up, up and away in my beautiful balloon flying broadband-bot
Slip your finger in this ring and unlock your backdoor, phone, etc
Take a look at this new NFC jewellery – why, what were you thinking of?
US mobile firms cave on kill switch, agree to install anti-theft code
Slow and kludgy rollout will protect corporate profits
prev story

Whitepapers

Securing web applications made simple and scalable
In this whitepaper learn how automated security testing can provide a simple and scalable way to protect your web applications.
Combat fraud and increase customer satisfaction
Based on their experience using HP ArcSight Enterprise Security Manager for IT security operations, Finansbank moved to HP ArcSight ESM for fraud management.
The benefits of software based PBX
Why you should break free from your proprietary PBX and how to leverage your existing server hardware.
SANS - Survey on application security programs
In this whitepaper learn about the state of application security programs and practices of 488 surveyed respondents, and discover how mature and effective these programs are.
3 Big data security analytics techniques
Applying these Big Data security analytics techniques can help you make your business safer by detecting attacks early, before significant damage is done.